On the world’s most hallowed annual-marathon course, on a spiffy, cool day, in a race full of world-class marathoners, Kenyan Geoffrey Mutai, 29, sprinted down a pulsating Boylston Street to break the Boston Marathon finish tape in 2:03:02, by far the fastest marathon ever run. His countryman Moses Mosop, 25, running his first marathon, crossed the line just 4 seconds later.

Both easily surpassed the current 2:03:59 marathon world record of Haile Gebrselassie. However, today’s Boston times will receive an asterisk in the record books, due to the point-to-point nature of the historic Hopkinton-to-Copley Square Boston course.

American marathon star Ryan Hall led through most of the first 10 miles, and eventually finished fourth in 2:03:58, five seconds behind third-place finisher Gebre Gebremariam, who won last fall’s New York City Marathon. Hall’s time is the fastest ever run by an American marathoner, eclipsing the former mark of Khalid Khannouchi, 2:05:38. Hall’s time will also get an asterisk in the books.

Mutai was arguably the pre-race favorite, based on his two 2010 marathons (2:04:55 and 2:05:10), and he looked smooth and strong every step of the race. At 20 miles, on the Newton hills, he broke away from the large, fast pack of 10 leaders who had passed the half-marathon in a sizzling 1:01:58. He seemed to have the race well in hand until Mosop caught him three miles later on the down side of Heartbreak Hill. This could have spelled trouble. Mosop has been a Kenyan internationalist since finishing fourth in the 2004 Olympic 10,000m, and ran a 59:20 half marathon last year in Italy.

But Mutai had an answer for the fast-charging Mosop, perhaps stung by his second-place finish in both of his quick marathons last year. “I was scared because my other colleague Makau got away from me in my last two marathons,” Mutai said. “But I had trained this time to sharpen myself at this point in the race, so I knew I could be strong. And then I pushed myself to go to the end in the last 600 meters.” For his world-fastest effort, Mutai earned $225,000, including $75,000 in world-best and course-record bonuses that will not be denied him by Boston organizers, asterisks or no.

Mosop, the marathon virgin, admitted to first-time nerves on the hills, where Mutai first gapped him. “The climb was difficult for me,” he said. “I have no experience in the marathon, so I was thinking maybe I need to take my time or I will not finish. After I caught Mutai, I tried to go with one kilometer remaining, but I was full tired.”

Gebremariam, 26, was the last of the original lead-pack runners to maintain contact with the top two finishers, but he was nearly a minute behind them when caught at 24 miles by a resurgent Ryan Hall, who had lost contact in the hills. “I think my time today was unbelievable and I say ‘thank you’ to Ryan Hall for pushing me the last two miles,” said a beaming Gebremariam to his American rival at the post-race press conference. “I am very happy. I didn’t see a 2:04 coming today–that is very, very fast. I didn’t train for a 2:04. I trained for a 2:06 or 2:07.”In his third consecutive Boston Marathon, Hall, 28, continued to improve his Boston times–from 2:09:40 to 2:08:41 to 2:04:58. His place finishes: third, fourth, fourth. “I felt very comfortable out there today, much more comfortable than in my other Bostons,” he said. “For a while, I felt like I was the only guy in the race.

“From my other Bostons, I’ve learned that I can come back later in the race if I just maintain my rhythm. This year, when I got dropped, I just tried to stay a little closer. I got very excited by the splits I was seeing in the Newton hills. I realized I was part of an event that was producing special things. It was a little crazy to think that I was on 2:04 pace and I couldn’t even see the leaders. When I caught Gebremariam, I wasn’t worried about who was going to win. I just wanted us to run as fast as possible.

“It doesn’t matter to me if someone thinks I’m the American marathon record holder or not. All I know is that I just ran a 2:04 marathon, and I’m very proud of that.”

Most of the elite athletes said they barely noticed any wind on the course. Regardless, it was one of those Bostons–they seem to happen about every 20 years or so–when conditions and competition conspired to produce amazing times. This was especially true in the men’s race where two runners beat the world-best time, four broke 2:06, and eight broke 2:08. (The previous high number of sub-2:08s at Boston was three in 1998.) The first four finishers broke the course record 2:05:52 run last year by Robert Kiprono Cheruiyot. The first seven finishers beat the 2:07:14 record that had stood until last April.

“I always seem to make my big breakthroughs in races where everyone else is breaking through even more,” noted Hall, a pretty good marathon historian. “I figure that one of these years I’ll have a breakthrough when no one else does.”

The fast times were set up by Hall’s aggressive frontrunning. At the Friday morning press conference, he had said that he felt like a “freight train,” and that’s how he ran, clocking 14:29 at 5K and 29:06 at 10K, with a dozen East Africans trailing close on his heels. The leaders hit the halfway point in 1:01:58, beating the checkpoint record of 1:02:01 set by Juma Ikangaa in 1990.

But those were the mostly downhill miles of the Boston course, which drops about 250 feet from start to finish.

Mutai then flew over the Newton hills, including fabled and feared Heartbreak, in 1:01:04 for his second-half split. That was an astonishing 1:11 under Cosmas Ndeti’s old record, 1:02:15, for the second half.

Standing at the finish line, Boston Marathon race announcer since 1979 (and now BAA executive director) Tom Grilk could scarcely believe his eyes as Mutai and Mosop sprinted toward him. Later, the always-eloquent Grilk described the moment. “You might only once in your lifetime have the opportunity to see someone do something better than it has ever been done before,” Grilk said. “It was simply astonishing to be the finish line announcer for this moment.”